18

Is there a way that I can make 

$ make

default to:

$ make -j 8

?

ROMANIA_engineer
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anon
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8 Answers8

71

Set the environment variable MAKEFLAGS to -j 8. If you are using csh or tcsh, you can do this with setenv MAKEFLAGS '-j 8'. If you are using bash, you can do this with export MAKEFLAGS='-j 8'. You might wish to put this command in your shell's start-up file, such as .cshrc or .bashrc (in your home directory).

Caution: Setting a default like this will apply to all invocations of make, including when you "make" a project other than your own or run a script that invokes make. If the project was not well designed, it might have problems when it is built with multiple jobs executing in parallel.

s4y
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Eric Postpischil
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12

The answers suggesting alias make='make -j 8' are fine responses to your question.

However, I would recommend against doing that!

By all means, use an alias to save typing - but call it something other than make.

It might be OK for whatever project you're currently working on; but it's quite possible to write makefiles with missing dependencies which do not quite work properly with -j, and if you encounter such a thing, you'll be left wondering why the build fails in a mysterious way for you but works fine for other people.

(That said, if you do alias make, you can get bash to ignore the alias by typing \make.)

Matthew Slattery
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10

alias make="make -j 8", assuming bash shell

David Wolever
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Anycorn
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    wait .. how does this not recursively call make i.e. make -> make -j 8 -> make -j 8 -j 8 -> make -j 8 -j 8 -j 8 – anon Jan 28 '10 at 01:08
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    The alias changes the make command to default 'make -j 8' It does not call the make command. – Gazler Jan 28 '10 at 01:11
  • This can also be placed in the .bashrc file so you don't have to enter it into each shell, .bashrc is in your home directory (in Debian at least). – Grundlefleck Jan 28 '10 at 01:52
4

Add

MAKEOPTS='-j8'
MAKEFLAGS='-j8'

to /etc/make.conf (create it if it doesn't already exist).

If that doesn't work, add

export MAKEOPTS='-j8'
export MAKEFLAGS='-j8'

to your system-wide profile (e.g., /etc/profile).

For me, MAKEOPTS alone didn't work. Possibly MAKEFLAGS is all that's needed.

Geremia
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  • Just so you would know, can't get this to work either. https://gist.github.com/sanmai/dcc31ae20afa6e8ba4721f174fe05fd9 – sanmai Feb 02 '18 at 00:23
  • Check the gist to see for yourself. `MAKEFLAGS` gets to keep only `-j`, without a digits – sanmai Feb 02 '18 at 04:06
  • @sanmai When I run that Makefile with GNU Make 4.2.1 (my `strings /usr/bin/make | grep MAKEOPTS` also outputs nothing), I get `' -j4 --jobserver-auth=3,4' must have --jobs=4`. – Geremia Feb 02 '18 at 04:41
  • Well, it seems like [they added this feature in 4.2](https://lists.gnu.org/archive/html/info-gnu/2016-05/msg00013.html). There's no easy way to get 4.2 in Debian now... – sanmai Feb 05 '18 at 01:23
3

If you are using the command line you can do:

alias make='make -j 8'

This will be temporary, to make it permanent you need to add it to .bashrc

Read here: http://www.linfo.org/make_alias_permanent.html

Gazler
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1

Why not create an outer makefile, that calls another makefile like this, this is replicated from the manual here.

     SUBDIRS = foo bar baz
     .PHONY: subdirs $(SUBDIRS)
     subdirs: $(SUBDIRS)
     $(SUBDIRS):
             $(MAKE) -j 8 -C $@

     foo: baz
t0mm13b
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1

If you're using GNU make:

$ make --version
GNU Make 4.2.1
Built for x86_64-alpine-linux-musl

...then I found that GNUMAKEFLAGS seems to work:

export GNUMAKEFLAGS=-j8
make

Disclaimer, I'm a n00b with the C toolchain so sorry if this isn't portable. It's working on Alpine Linux 3.8 (in Docker) though.

Tom Saleeba
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-1

You could move /usr/bin/make to /usr/bin/make_orig and make /usr/bin/make this script:

#!/bin/sh

/usr/bin/make_orig -j 8 $@

Be sure to run chmod +x /usr/bin/make.

Try this method if the simpler method in my other answer doesn't work. This method isn't as safe and is a bit of a kludge.

Geremia
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  • This is just plain bad. Imagine if you ever need to update your make binary. – sanmai Feb 01 '18 at 09:11
  • @sanmai Yes, MAKEOPTS is much better; cf. [my other answer above](https://stackoverflow.com/questions/2151605/make-make-default-to-make-j-8/42658101#42658101). – Geremia Feb 01 '18 at 15:11